Claims:We claim:
1. A device for dehydrating low density food material(s), the device comprising:
i. a zone comprising a radiation absorbing zone (RAZ) (101) and a material handling zone (MAZ) (102),
wherein area of the RAZ (101) is varied from 20% to 70% of total area of zone,
wherein area of the MAZ (102) is varied from 30% to 80% of total area of zone and height of MAZ (102) is varied from 2cm to 50cm,
wherein distribution area between RAZ (101) and MAZ (102) is optimized according to density of the food material(s) (103) and moisture load;
ii. a lid (104) for covering zone; and
iii. a unit (105) for collecting and removing water/moisture,
wherein the unit (105) is suitably positioned at lid (104).
2. A process for dehydrating low density food material(s), wherein the process comprises:
i. pre-treating food material(s) to obtain a treated food material(s) (103) with density in the range of 50-300 kg/m3;
ii. exposing the treated food material(s) to material Handling Zone (MAZ) (102) for a suitable drying conditions to obtain a dried food material;
wherein radiation energy is transferred from Radiation absorption Zone (RAZ) (101) to MAZ (102); and
iii. supplying additional energy to RAZ (101) and/or MAZ (102) to obtain a dehydrated food product(s) (103);
wherein the dehydrated food product(s) has water activity in the range of 0.1-0.5.
3. A process for dehydrating low density food material(s), wherein the process comprises:
i. pre-treating food material(s) to obtain a treated food material(s) (103) with density in the range of 50-300 kg/m3;
ii. exposing the treated food material(s) to material Handling Zone (MAZ) (102) for a suitable drying conditions to obtain dehydrated food product(s) (103); wherein radiation energy is transferred from Radiation absorption Zone (RAZ) (101) to MAZ (102); and
iii. optionally supplying additional energy to RAZ (101) and/or MAZ (102) to obtain a dehydrated food product(s) (103);
wherein the dehydrated food product(s) has water activity in the range of 0.1-0.5.
4. The process as claimed in claim 2 and 3, wherein food material (103) is selected from fruits, vegetables, marine products, spices, grains, meat products.
5. The process as claimed in claim 2 and 3, wherein pre-treating is selected from cutting, chopping, shredding, peeling.
6. The process as claimed in claim 2 and 3, wherein pre-treating is partially heating/drying.
7. The process as claimed in claim 2, 3 and 6, wherein treated food material is exposed at a temperature in the range of 300C to 800C and time period in the range of 1 hr to 8 hrs.
8. The process as claimed in claim 2 and 3, wherein the dehydrated food product has water activity in the range of 0.1 to 0.5.
9. The device for dehydrating low density food material(s) as claimed in claim 1, wherein the device is radiation-conduction dryer.
10. The process for dehydrating low density food material as claimed in claim 2 and 3 is carried out by using the device as claimed in claim 1.
, Description:Field of invention
Present invention relates to a radiation-conduction device for dehydrating low density food material(s). Furthermore, it relates to a process for dehydrating low density food material(s) using said device. The device has wide applications in food industry.

Background of invention
Drying is one of the oldest preservation processes available to the mankind. Dried foods play an important role in the food supply chain. Fruits, vegetables, grains etc. are commonly dried for application in the food industry. The main feature of this process relies on lowering the water content in order to avoid or slow down food spoilage by microorganism. Some common words used for lowering water content are "drying" or "dehydration", or even "dewatering". There are various aspects that must be considered when drying small fruits and vegetables, whether for the food or nutraceutical and functional food industries. There are various conventional and new drying technologies. There may be carried out pre-treatment methods before drying foods/food material(s) which are based upon drying efficiency, quality preservation, and cost effectiveness.

The drying method can affect the nutritional content of the finished product. Product deterioration is usually due to the application of excess heat, rather than the moisture removal. Drying types can be classified by either the mechanism of heating or mechanism of vapour transport. For example air drying requires a high temperature air which supplies the heat and removes the water vapour, whereas vacuum drying uses a reduction in pressure to remove the vapour.

Various methods used for drying includes sun/solar drying, freeze drying, drum drying, spray drying, vacuum drying, tray drying etc. Conventional methods of drying involve convection and radiation heating to remove the moisture. The preservation of foods by drying is the time-honoured and most common method used by humans and the food processing industry.

Presently used solar drying devices suffers from various drawbacks such as low efficiency, non-uniform removal of moisture, huge operating cost and therefore economically not feasible, lesser shelf life of product, loss of volatile compounds, contamination from environment, huge floor space requirement, inconsistency in sensory quality of the product, large labour requirement etc.

Therefore, to overcome above mentioned problems in the prior art, there is a need to develop dryer/device that uses conduction, convection and radiation modes of the drying the food material(s) and provides better efficiency, controlled environment of drying, better product quality etc. and dehydrate low density, low moisture load material to remove unbound moisture.

Objects of present invention

An object of the present invention is to provide a device for dehydrating low density and low moisture containing food material(s).

Another object of the present invention is to provide a process for removal of unbound moisture of low-density food material(s).

Other object of the present invention is to provide radiation-conduction device for dehydrating food material(s).

Further object of the invention is to provide a device and process for removal of unbound moisture of low-density food product(s).

Another objective of the present invention is to provide a process for drying of fruit, vegetables, spices and marine products using the said device.

Yet another object of the invention is to develop a device that has wide applications in food industry.

Summary of present invention
The main aspect of the present invention is to provide a device for dehydrating low density food material(s), the device comprising:
i. a zone comprising a radiation absorbing zone (RAZ)(101) and a material handling zone (MAZ) (102),
wherein area of the RAZ (101) is varied from 20% to 70% of total area of zone, wherein area of the MAZ (102) is varied from 30% to 80% of total area of zone and height of MAZ (102) is varied from 2cm to 50cm,
wherein distribution area between RAZ (101) and MAZ (102) is optimized according to density of the food material(s) (103) and moisture load;
ii. a lid (104) for covering zones; and
iii. a unit (105) for collecting and removing moisture,
wherein the unit (105) is suitably positioned at lid.

Another aspect of present invention is to provide a process for dehydrating low density food material(s), wherein the process comprises:
a) pre-treating food material(s) to obtain a treated food material(s) (103) with density in the range of 50-300 kg/m3;
b) exposing the treated food material(s) to material Handling Zone (MAZ) (102) for a suitable drying conditions to obtain a dried food material;
wherein radiation energy is transferred from Radiation absorption Zone (RAZ) (101) to MAZ (102); and
c) supplying additional energy to RAZ (101) and/or MAZ (102) to obtain a dehydrated food product(s) (103);
wherein the dehydrated food product(s) has water activity in the range of 0.1-0.5.

Brief description of figure
Figures given in the specification are for illustration purpose only and shall not limit scope of the invention.
Figure 1 illustrates all elements of device for dehydrating food materials.
Figure 2 illustrates RAZ (101) (crest region) and MAZ (102) (trough region) in trapezoid with food material (103) with varying size of RAZ (101) and MAZ (102).
Figure 3 illustrates RAZ (101) (crest region) and MAZ (102) (trough region) in wave shape with food material (103) with varying size of RAZ (101) and MAZ (102).

Detailed description of present invention
In the present invention, numbers of terms are used for description of invention. The definitions of terms are as follows.
Definition:
The term ‘food’ or ‘food material(s)’ (103) used herein refers to material(s) to be dehydrated include such as but not limited to fruits, vegetables, spices, meat, grains and marine products. Food material majorly involves agriculture products and having water activity in the range of 0.1-0.9.

The terms ‘food’, ‘food material(s)’ can be used interchangeably in the specification.

The term ‘food product(s)’ used herein refers to a processed food material or dehydrated food materials include such as but not limited to fruits, vegetables, spices, meat, grains, agriculture products, marine products and having water activity in the range of 0.1 to 0.5

The term ‘pre-treating’ used herein refers to any process that makes surface area of food material(s) more available for drying include such as but not limited to cutting, chopping, shredding, peeling etc. It may also involve partially drying.

The term ‘Radiation Absorbing Zone (RAZ)’ (101) used herein refers to the zone for absorbing solar light and convert it into heat energy.

The term ‘Material Handling Zone (MAZ)’ (102) used herein refers to zone for handling of food material or food product.

The term ‘zone’ used herein refers to area provided for RAZ (101) and MAZ (102).

The term ‘dehydrating’ used herein refers to a process for removing bound and unbound water/moisture of food material(s), wherein the said food material(s) has water activity in the range of 0.5-0.9

One of the embodiments of present invention provides a device for dehydrating low density food material(s), the device comprising:
i. a zone comprising a radiation absorbing zone (RAZ) (101) and a material handling zone (MAZ) (102),
wherein area of the RAZ (101) is varied from 20% to 70% of total area of zone, wherein area of the MAZ (102) is varied from 30% to 80% of total area of zone and height of MAZ (102) is varied from 2cm to 50cm,
wherein distribution area between RAZ (101) and MAZ (102) is optimized according to density of the food material(s) (103) and moisture load;
ii. a lid (104) for covering zone; and
iii. a unit (105) for collecting and removing water/moisture,
wherein the unit is suitably positioned at lid.

Another embodiment of present invention provides a device for dehydrating low density food material(s), the device comprising:
i. a radiation absorbing zone (RAZ) (101),
wherein area of the RAZ is varied from 20% to 70% of total area of the zone;
ii. a material handling zone (MAZ) (102),
wherein area of the MAZ (102) is varied from 30% to 80% of total area of the zone and height of MAZ (102) is varied from 2cm to 50cm;
iii. a lid (104) for covering zone; and
iv. a unit (105)for collecting and removing water/moisture,
wherein the unit is suitably positioned at the lid;
wherein distribution area between RAZ (101) and MAZ (102) is optimized according to density of the food material(s) and moisture load.

Another aspect of present invention is to provide a process for dehydrating low density food material(s), wherein the process comprises:
i. pre-treating food material(s) to obtain a treated food material(s) (103) with density in the range of 50-300 kg/m3;
ii. exposing the treated food material(s) to material Handling Zone (MAZ) (102) for a suitable drying conditions to obtain a dried food material;
wherein radiation energy is transferred from Radiation absorption Zone (RAZ) (101) to MAZ (102); and
iii. supplying additional energy to RAZ (101) and/or MAZ (102) to obtain a dehydrated food product(s) (103);
wherein the dehydrated food product(s) has water activity in the range of 0.1-0.5.

Another aspect of present invention is to provide a process for dehydrating low density food material(s), wherein the process comprises:
i. pre-treating food material(s) to obtain a treated food material(s) (103) with density in the range of 50-300 kg/m3;
ii. exposing the treated food material(s) to material Handling Zone (MAZ) (102) for a suitable drying conditions to obtain a dehydrated food product(s) (103); wherein radiation energy is transferred from Radiation absorption Zone (RAZ) (101) to MAZ (102); and
iii. optionally supplying additional energy to RAZ (101) and/or MAZ (102) to obtain a dehydrated food product(s) (103);
wherein the dehydrated food product(s) has water activity in the range of 0.1-0.5.

Another embodiment of present invention provides a process for dehydrating low density food material(s), the process comprising:
i. pre-treating food material(s) (103) to obtain a treated food material(s) with density in the range of 50-300 kg/m3;
ii. exposing the treated food material(s) with radiation absorbing zone (RAZ) (101) for a suitable drying conditions to obtain a dried food material(s),
wherein radiation energy is converted into heat energy; and
iii. transferring the dried food material(s) into a material handing zone (MAZ) (102) and supplying additional energy to obtain a dehydrated food product(s),
wherein the dehydrated food product(s) has water activity in the range of 0.1-0.5.

Another embodiment of present invention provides Radiation Absorbing Zone (RAZ) (101) and Material Handling Zone (MAZ) (102), wherein RAZ (101) forms crest region/share and MAZ (102) forms trough region/shape for handling food material (103). Fraction of RAZ (101) and MAZ (102) can be varied as per the requirement. Both Trough and Crest region/shape gives advantage to process food material easily and effectively. Furthermore, crest and trough region of RAZ (101) and MAZ (102) are in wave shape or in trapezoid shape or in triangle shape.

Another embodiment of present invention provides a process for dehydrating low density food material(s), wherein food material (103) is selected from fruits, vegetables, marine products, spices, grains, meat products.

Another embodiment of present invention provides a process for dehydrating low density food material(s), wherein the food material has initial water activity in the range of 0.1-0.9.

Another embodiment of present invention provides a process for dehydrating low density food material(s), wherein the partially dried or dried food material has moisture content in the range of 15% to 66%.

Another embodiment of present invention provides a process for dehydrating low density food material(s), wherein pre-treating is selected from cutting, chopping, shredding, peeling.

Another embodiment of present invention provides a process for dehydrating low density food material(s), wherein pre-treating is partially heating/drying.

Yet another embodiment of present invention provides a process for dehydrating low density food material(s), wherein suitable drying conditions comprises temperature, pressure, time period.

Yet still another embodiment of present invention provides a process for dehydrating low density food material(s), wherein the pre-treated food material(s) is exposed for time period in the range of 1 hour to 24 hours.

Yet still further embodiment of the present invention provides a process for dehydrating low density food material(s), wherein the treated food material is exposed at a temperature in the range of 25oC to 80oC.

Yet still further embodiment of the present invention provides a process for dehydrating low density food material(s), wherein the treated food material is exposed at a temperature in the range of 25oC to 80oC.

In an embodiment of present invention, the partially dried food material(s) has moisture content in the range of 5% to 85%.

Another embodiment of present invention provides a device for dehydrating food material(s), wherein the distribution of area between RAZ and MAZ can be optimized for the given material’s density and moisture content by varying the height of MAZ as the operating parameter to maximize the efficiency of the dryer with the following formula:
Height of MAZ = 4 * Fractional area of RAZ / (1- Fractional area of RAZ) * (Density of material * moisture content difference between initial and the final product)

Yet another embodiment of present invention provides a device for dehydrating food material(s), wherein the energy requirement from RAZ is not enough. Then additional energy can be supplied to MAZ by direct convection, conduction or radiation with the following formula:
Power supplied to MAZ = (Moisture to be removed per unit time * latent heat of vaporization of water) – (Fractional area of RAZ * Radiation intensity on RAZ)

In an embodiment of present invention, said process is helped in maintaining colour and micronutrients of food products.

Another embodiment of present invention provides a process wherein the dehydrated food product has water activity in the range of 0.1-0.5

In preferred embodiment of present invention, the device for dehydrating low density food material(s) is radiation-conduction dryer/solar dryer.

Example:
The following examples are given by the way of illustration of the present invention and should not be construed the limit the scope of present disclosure.

1. Dehydrating Pineapple using dryer
10 kg of pieces of pineapples were taken and pre-dried at a temperature 600C for 4 hours to obtain partially dried/dried pineapple. This partially dried/dried pineapple was transferred into a material handing zone (MAZ) (102) and dehydrated for 6 hour by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated pineapple obtained has 0.4 water activity.

2. Dehydrating Banana using dryer
8 kg of slices of banana were taken and pre-dried at a temperature 500C for 4 hours to obtain partially dried/dried banana. This partially dried/dried banana was transferred into a material handing zone (MAZ) (102) and dehydrated for 8 hours by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated banana obtained has 0.4 water activity.

3. Dehydrating tomato using dryer
5 kg of chopped tomato were taken and pre-dried at a temperature 450C for 8 hours to obtain partially dried/dried tomato. This partially dried/dried tomato was transferred into a material handing zone (MAZ) (102) and dehydrated for 6 hours by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated tomato obtained has 0.45 water activity.

4. Dehydrating Bombay duck using dryer
10 kg of Bombay duck were sliced into small pieces and treated with salt further pre-dried at a temperature 450C for 8 hours. This partially dried/dried pieces were transferred into a material handing zone (MAZ) (102) and dehydrated for 8 hours by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated Bombay duck obtained has 0.5 water activity.

5. Dehydrating Turmeric using dryer
7 kg of turmeric were taken and pre-dried at a temperature 450C for 4 hours to obtain partially dried/dried turmeric. This partially dried/dried turmeric was transferred into a material handing zone (MAZ) (102) and dehydrated for 6 hours by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated turmeric obtained has 0.4 water activity.

6. Dehydrating Sweet corn using dryer
8 kg of sweet corn were taken and pre-dried at a temperature 450C for 6 hours to obtain partially dried/dried sweet corn. This partially dried/dried sweet corn was transferred into a material handing zone (MAZ) (102) and dehydrated for 8 hours by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated sweet corn obtained has 0.3 water activity.

7. Dehydrating chicken strips using dryer
10 kg of chicken strips were taken and pre-dried at a temperature 450C for 8 hours. This partially dried/dried chicken strips was transferred into a material handing zone (MAZ) (102) and dehydrated for 8 hours by energy supplied from Radiation Absorption Zone (RAZ) (101). The dehydrated chicken strips obtained has 0.35 water activity.

Similarly drying of various food material was carried out at various parameter to obtain final product as per the requirement. Details of the same are provided below table.
Sr. No. Food material Weight (kg) Density (kg/m3) Water activity Temp
(0C)
Time
(hr)

Initial Final Initial Final Initial Final
1. Pineapple 100 80 100 50 0.5 0.1 30 3
2. Banana 100 78 100 75 0.6 0.4 45 8
3. Tomato 100 45 135 100 0.65 0.3 55 3
4. Bombay duck 100 70 150 135 0.7 0.4 60 4
5. Turmeric 100 80 200 150 0.7 0.5 70 1
6. Sweet corn 100 60 250 170 0.8 0.5 75 8
7. Chicken strips 100 65 300 200 0.8 0.5 80 8